Low insertion force is a widely sought goal in connection devices. Integrated circuit (IC) chips are made by a number of manufacturers and the standards for typical IC housings such as dual in-line packages (DIP's) are not rigid. Normally IC DIP's have contact legs which splay outward and must be captured and straightened as they are guided into engagement with the socket by man or machine by means of the lead-in surfaces or chamfers. Most such chamfer surfaces are straight and do little to reduce mating force. Techniques such as lubrication, forming the DIP's with straight legs, and using a mechanism to clamp the legs, often add significantly to the cost of the DIP and DIP sockets and do not always significantly reduce insertion force.
In other situations, too, reduction of insertion force is desirable: plug and socket and pin and jack. One approach in this area is disclosed in U.S. Pat. No. 4,090,772, with respect to a pin and socket of circular cross section in which the pin and socket size and shape are constrained to a limited region and the surface finish carefully controlled.
When high peak forces of insertion are encountered the device must be "overdesigned" in order to accommodate that peak force, even though that peak force may be only momentary and force during the rest of the insertion is much lower than the peak force.